Fixed-Point Theory on a Frechet Topological Vector Space

Abstract EN

We establish some versions of fixed-point theorem in a Frechet topological vector space E.

The main result is that every map A=BC (where B is a continuous map and C is a continuous linear weakly compact operator) from a closed convex subset of a Frechet topological vector space having the Dunford-Pettis property into itself has fixed-point.

Based on this result, we present two versions of the Krasnoselskii fixed-point theorem.

Our first result extend the well-known Krasnoselskii's fixed-point theorem for U-contractions and weakly compact mappings, while the second one, by assuming that the family {T(⋅,y):y∈C(M) where M⊂E and C:M→E a compact operator} is nonlinear φ equicontractive, we give a fixed-point theorem for the operator of the form Ex:=T(x,C(x)).